Using Radio Frequency Identification (RFID) for … 1805 Inventory and Monitoring Using Radio...

1419 1805Inventory and Monitoring

Using Radio Frequency Identification (RFID) for Monitoring Trees in the Forest:

State-of-the-Technology Investigation

United States Department of Agriculture

ForestService

National Technology & Development Program

April 2014

The information contained in this publication has been developed for the guidance of employees of the Forest Service, U.S. Department of Agriculture, its contractors, and cooperating Federal and State agencies. The Forest Service assumes no responsibility for the interpretation or use of this information by other than its own employees. The use of trade, firm, or corporation names is for the information and convenience of the reader. Such use does not constitute an official evaluation, conclusion, recommendation, endorsement, or approval of any product or service to the exclusion of others that may be suitable.

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Using Radio Frequency Identification (RFID) for Monitoring Trees in the Forest: State-of-the-Technology Investigation

Rey Farve, Project LeaderForest ServiceNational Technology & Development CenterInventory and Monitoring Program

April 2014

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TABLE OF CONTENTSI. INTRODUCTION ................................................................................................................................ 1 A. Background and Need ................................................................................................................ 1 1. FIA program ............................................................................................................................ 1 2.Needasidentifiedbyproposer ................................................................................................ 3

B.ObjectiveofInvestigation ............................................................................................................. 4

C. Technology Not Considered in the Investigation .......................................................................... 4 1. Barcode technology ................................................................................................................. 4

II. RFID TECHNOLOGY ......................................................................................................................... 4 A. Passive Tag – Active Reader ....................................................................................................... 5

B. Active Tag – Passive Reader ....................................................................................................... 6

C. Semi-Passive Tag – Active Reader .............................................................................................. 7

D.Application/UsageofRFIDTechnology ....................................................................................... 8 1.GeneraluseofRFID ................................................................................................................ 8 2.RFIDtechnologyuseinforestry .............................................................................................. 8

III. INVESTIGATION............................................................................................................................... 9 A. RFID Tags Investigated ................................................................................................................ 9 1. Semi-passive tags ................................................................................................................... 9 2. Passive tags ............................................................................................................................ 9

B. RFID Readers Investigated ........................................................................................................ 11

IV. FIELD TESTING THE MAXIMUM READ RANGE OF RFID TAGS AND READERS ................... 12 A. Indoor Test ................................................................................................................................. 12

B. Outdoor Test ............................................................................................................................... 13

V. CONCLUSIONS AND RECOMMENDATIONS ................................................................................ 15

VI. LITERATURE CITED...................................................................................................................... 17

APPENDIX ........................................................................................................................................... 19

A. PHOTOS OF RFID TAGS TESTED ................................................................................................ 21

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I. INTRODUCTIONForFiscalYear2013,GretchenNicholas(PacificNorthwestResearchStation,ForestInventoryandAnalysis(FIA)programmanager)submittedaproposaltotheNationalTechnologyandDevelopmentProgram’sInventoryandMonitoringSteeringCommitteetoinvestigatethestate-of-the-technologyofradiofrequencyidentification(RFID)foruseinrelocatingandmonitoringtreesintheforestenvironment.

RFIDtechnologyinvolvesawireless,non-contactsystemthatusesradiofrequencyelectromagneticfieldstotransferdatafromatag(attachedtoanobject)forautomaticidentificationand/ortracking.Thistechnology has advanced rapidly over the past decade.

TheproposalwasarequestfortheNationalTechnologyandDevelopmentProgramtoinvestigatewhether(ornot)RFIDtechnologyhasadvancedsuchthatitmightbeapractical,cost-effectivetoolfortheinventoryingandmonitoringoftreesonforestlands(especiallyfortheFIAprogram).

A. Background and Need

1. FIA programThe Forest Service’s Forest Inventory and Analysis (FIA) program providestheinformationneededtoassessAmerica’sforests.TheFIAprogramprovidesacontinuous,nationwideforestcensusthatprojectshowforestsarelikelytoappear10to50yearsinthefuture.ThisenablestheFIAprogramtoevaluatewhethercurrentforestmanagementpracticesaresustainableoverthelongterm.

Thenationwideforestcensusrequirescontinuous,periodiccollectionoffielddatatogeneratereportsonstatusandtrends:inforestareaandlocation;inthespecies,size,andhealthoftrees;intotaltreegrowth,mortality,andremovalsbyharvest;inwoodproductionandutilizationratesbyvariousproducts;andinforestlandownership.

TheFIAprogramismanagedwithintheForestService’sResearchandDevelopmentorganizationincooperationwithStateandPrivateForestryandNationalForestSystems.

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Figure 1—FIA Program at PNW Research Station. See http://www.fs.fed.us/pnw/pubs/fia.pdf

Currently,forthenationalcensus,FIAmonumentsforestplotsandtreeswithmetaltags,whichassistinrelocating(revisiting)plots10yearslaterforremeasurement.Frequently,afterseveralyears,treeshaveconsumedthetagsortagsareotherwiselost.SinceRFIDtechnologyhasadvancedsignificantlyoverthepastfewyearsandisbeingusedinwiderapplications,theproposerspeculatedthatpassiveorsemi-passive RFID technology (see RFID technology discussion in section II) may have advanced to a pointthatthistechnologymightbeacost-effectivetooltotagtreesonaforestplot.

Iftreesonplotscouldbetaggedwithaninexpensive,durable,long-livedRFIDtagthatstoresall(ormost)ofthetree’spertinentdata(e.g.,location,species,height,diameter,crowncover,health,etc…),aresearcherwithanRFIDreadermighteasilyrelocatetreesonplots10yearslater.Additionally,ifthepreviousinformationaboutthetreecouldberetrievedeasilyandnew(remeasurement)datauploadedeasily,thetimeinvolvedinthedatacaptureprocess(i.e.,collectionofpreviousdataandrecordingofnewremeasurementdata)ontherevisitedplotscouldbegreatlyreduced.Thiswouldreducecostsassociatedwithdatacaptureperplot.

As such, the National Technology and Development Program’s Inventory and Monitoring Committee identifiedthescopeofthisinvestigationas:“Investigate and demonstrate an electronic tracking method for locating trees and plot centers over time.”

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2.NeedasidentifiedbyproposerSanDimasstaffcontactedtheproposerinMarch2013todeterminethespecificneedsoftheFIAprogramfromRFIDtechnology.Table1identifiesparametersthatwouldbeconsideredideallysuitablefortheFIAprogramandparametersthatshouldbeconsideredunsuitable(notacceptable).TheparametersidentifiedasacceptablearethosethatmightbemoresuitableforotherforestersinResearchandDevelopmentortheNationalForestSystem(thatis,foresterswithintheagencythatarenotpartoftheFIAprogram).

Ideally,theproposerfeltthattheFIAprogramwouldbenefitfromRFIDtechnologythatallowedasurveyortobeabletorevisitaFIAforestplotcenterandquerytheinformationonallRFIDtagsthatwereattachedtotreesintheplotareaonthepreviousvisit(10yearsprior).Thereadrangeofthetagsshouldbe20feet(orgreater)forthetechnologybeasignificantimprovementoverthecurrentmethodofphysicallysearchingformetaltagsattachedtotrees.Also,theGPSlocationinformationstoredontheindividualtreetagsshouldenabletreestobemorereadilyrelocated.

Oncerevisited,thetreecouldberemeasured,andthisupdatedinformationuploadedtotheoriginaltag(orthetagcouldbereplaced,ifnecessary).Sinceseveralhundredtreesaremeasured(andremeasured)intheFIAprogram,tagswouldhavetobeinexpensiveandthetag-to-treeattachmentmustbesimpleandfast.

Table 1—Need/requirements of FIA of RFID technology for use in monitoring trees

Performance Requirement

Parameter IDEAL ACCEPTABLE* NOT ACCEPTABLE

Read range >20ft. 5-10ft. <3ft.Cost (per tag) < $ 0.10 $ 0.15 - $ 0.45 > $ 0.50Lifespan/durability 12+ yrs. 8-9 yrs. < 5 yrs.

Tag-to-tree attachment

Manual,simple,withlightweighttool Intermediate

Needs heavy tool(s),

complicated

ProgrammabilityFully and easily programmablein

thefield

Inoffice–(withsimpletreenumber) ---

Read accuracy 100% --- < 99%*RequirementsthatmightbemoreacceptabletootherforestersinR&Dand/orNFS

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B. Objective of InvestigationTheobjectiveofthisstudyistoinvestigatethecurrentstateofRFIDtechnology–especiallyasitrelatestopractical,cost-effectiveusewithintheforestenvironment.TheinvestigationfocusesonneedsthattheFIAprogramconsideredasimportantformonitoringtrees.

SanDimasstaffenlistedthesupportofDonLimuti,electronicsengineer,NationalTechnologyandDevelopment Center, Missoula, MT. in the investigation.

C. Technology Not Considered in the Investigation 1. Barcode technologyBasedontheneedsidentifiedbytheproposer,barcodetechnologyisnotconsideredacceptable(orpracticable)forFIAuseonforestplotsforthefollowingreasons:

• Barcodesmustbeinthereader’sline-of-sight(i.e.,notobscuredbyotherobstacles/vegetation).

• Readersmustbe(atmost)withinafewfeetofthebarcode.

II. RFID TECHNOLOGY Unlessotherwisecited,mostoftheinformationinthissectionwasobtainedfrom:

en.wikipedia.org/wiki/RFID.

rfid.net/basics.

calpoly.edu/tutorial.htm.

Karygiannis et al. 2007.

RFIDtechnologyinvolvesawireless,non-contactsystemthatusesradio-frequencyelectromagneticfieldstotransferdatafromatag(attachedtoanobject)forautomaticidentificationand/ortracking.AtypicalRFIDsystemconsistsofaninterrogator(alsocalledareader),andatransponder(commonlyreferredtoasatag)(figure2).Thetagisusuallyattachedtoanobjectthatistobeidentified.

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READER

power for tag and reader

backscatterd signal

Tag

Figure 2—Typical RFID system consists of a reader and a tag. The reader sends radio waves to the tag that contains its identifying information. The tag responds to the reader with its information.

Radiotransmissionsareusedbythereadertosendaquerytothetagandbythetagtoreturnananswer,generallycontainingidentifyinginformation.Thereaderalsocanbeconnectedtoahostcomputer,whereinformationcanbeincorporatedintoadatabase.

ThethreebasictypesofRFIDsystemsare:(1)PassiveTags–ActiveReaders;(2)ActiveTags–PassiveReaders;and(3)anintermediatesystemofSemi-passiveTags–ActiveReaders.

ThefollowingdiscussionistheresultofabriefliteraturesearchthatstaffconductedonRFIDtechnology.

A. Passive Tag – Active Reader Passivetagshavenopoweroftheirown;instead,allthepowerneededtooperatethetagisderivedfromtheradiosignalssentbythereader.Furthermore,passivetagshavenoconventionalradiotransmitterand,assuch,cannotcreatetheirownsignal.Instead,theyvarytheelectricalloadattachedtotheantennainordertovarythesignalreflectedfromtheantenna,somewhatanalogoustousingamovablemirrortosendasignalbyreflectingthelightofthesuntowardsawatcher.Thistechniqueisknownasbackscattercommunications.Backscattercommunicationsalsorequirethatthetagandreaderbeincloseproximity(withinafewfeet)ofeachotherwhenthetransmittedradiowavesarelowfrequency(LF)orhighfrequency(HF).Withtheemergingtechnologythattransmitultra-highfrequency(UHF)radiowaves,longerreadrangesarebecomingpossible1;someUHFRFIDmanufacturersclaimreadrangesaslongas15to20feet.Sincemetalandwater(ormoisture)tendtoabsorbUHFwaves,considertheirpresencewhenevaluatingUHFtagsreadranges.

1ForadiscussionofthedifferencesbetweenHFandUHFRFID,seeIntermecTechnologiesCorporation(2007).

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Passivetagsoftenareextremelysimpledevices(figure3).Thetypicalstructureconsistsofaplasticsubstrateorinlay,aprintedoretchedmetalantenna,andasingleintegratedcircuit.Asaconsequence,passivetagscanbemuchsmallerandlessexpensivethanothertypesofradiodevices.AUHFpassivetagwithanantennacanbepurchasedinbulkfornickelspertag.

READER

power for tag and reader

backscatterd signal

TagBattery/power

Passive Tag/Active Reader Less than $ 0.10

Last 10 -20 yrs

1 in. to 20 ft.Read Range

Figure 3—RFID system that consists of a passive (non-powered) tag and an active (powered) reader.

Apassivetagrequiresnomaintenance,andhasalonglifetime,limitedbydegradationofthetagmaterialsratherthanbatteryusage.Itisreasonabletoexpectthatinmanyenvironmentspassivetagswillbereadablefor10to20years.

B. Active Tag – Passive ReaderThisRFIDsystemistheoppositeoftheonedescribedinsectionII.A.IntheActiveTag–PassiveReadersystem,thetagispoweredandthereaderhasnopower(figure4).Inessence,anactiveRFIDtagisequippedwithitsownradiotransmitter,suchasacellphoneorWiFiclient.

Activetagsuseconventionalcircuitryfortransmissionandreceptionwithreadrangeandreliabilitysimilartotheperformanceofotherradios.Assuch,readrangesofhundredsofmeterstokilometers(miles)areachievable,andtagscanbereaddespitesubstantialobstructionsbetweenthetagandreader.

Withimprovedreadrangeandreliabilitycomesincreasedcost,size(circuitcomplexity),andmaintenancerequirements.Activetagscostmorethan$20each;somecostasmuchas$100eachandaredesignedfortrackinghigh-valueassets.

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Tag

battery

Active Tag /Passive Reader

READERTransmitted signal

from tag

$20.00 - $100 .00Last 3- 5 yrs

> 1500 ft Read Range

Figure 4—RFID system that consists of an active (powered) tag and a passive (non-powered) reader.

Thistechnologyisnotpractical(orcost-effective)fortheneedsidentifiedinthisinvestigationandwillnotbeinvestigated/evaluatedfurther.ReadersinterestedinmoredetailsonActiveTagRFIDtechnologyshouldseethereferences/linksprovidedatthebeginningofthissection.

C. Semi-Passive Tag – Active ReaderThisRFIDsystemisintermediatebetweenthetwosystemsdiscussedinsectionsII.AandII.B.IntheSemi-Passivetag–ActiveReaderSystem,thereaderispoweredandthetaghasabatterytopowerthetag’scircuitry;thetag,however,stillemploysbackscatteringorloadmodulationtocommunicatewiththereader(figure5).

Semi-passivetagsrequirethatthereadersignalbelargeenoughtodecipherbutdoesnotneedtoextractpowertorunthetag’scircuitry.Therefore,thereadrangeisnotlimitedtoafewfeet(aswithapassivetag).Thereadrangeofsemi-passivetagsusuallyislimitedbytherapiddecreaseinthereadersignal;however,high-qualityreceiverscanachievereadrangesontheorderof300feetinunobstructedareas.

Inadditiontolongerrange,semi-passivetagsprovidemuchbetterreliabilityatshortranges.Apassivetagatseveralfeetfromareadermightnotreadthetagifthetransmissionpath(oftheradiowaves)fromtagtoreaderisblockedbyanobstacle.Asemi-passivetagatasimilardistanceisoftenbettertodecipher and reply to the reader’s signal.

Adownsideofsemi-passivetagsisthattheyaremoreexpensivethanpassivetags;furthermore,theirapplicabilityislimitedbybatterylife.Manufacturersofsemi-passivetagstrytoensurethatmostofthecircuitryisswitchedoffexceptwhenthetagisbeingqueriedbyareader;batterylifeisstillgenerallylimitedtoonlyafewyears.

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READER

power for signal (from reader )

backscatterd signal

Tag

batteryBattery /power

Semi -passive Tag /Active Reader

$3.00 - $10 .00Last 3-5 yrs

< 300 ft Read Range

Tag circuitry powered by battery

Figure 5—RFID system that consists of a semi-active (powered) tag and an active (powered) reader.

D. Application/Usage of RFID Technology 1.GeneraluseofRFIDRFIDisusedinnumerousapplicationsanditisprojectedtobecomemorewidespreadinthefuture.ForageneraldiscussionofRFIDhistory,usage,andcostseeRoberts(2006)andZhuetal.(2012).

Ferreretal.(2010)provideadetaileddiscussionofhowRFIDcanbeusedtoenhanceawidevarietyofservicedeliveryoperations(e.g.,freewaytollcollection,librarymaterialtracking,hospitalpatienttracking, cargo tracking, retail cashless payment, and several others). They reported that most industriesbenefitedbyreplacementoflaborthroughautomation,cycletimereductions,enablingself-service, and/or inventory control/loss prevention.

ForadiscussionofRFIDuse(andchallengestousage)intheagricultureindustryseeRuis-GarciaandLunaei (2011).

2.RFIDtechnologyuseinforestryAccordingtoourliteraturereview,thesuggestedapplicationofRFIDforforestryisfortrackinglogsthroughtheforestrysupplychainandisreportedbyEuropeanforesters(GermanyandFinland).KortenandKaul(2008)werethefirsttoreportonthefeasibilityofusingapassiveRFIDtagtotracklogsastheymovedthroughthesupplychain.However,theshortreadrangeoftheHFtagsusedinthepilotstudy(6inchesto1foot)madereadingtagsasignificantchallenge.

Hakiietal.(2010)andBjorketal.(2010)reportonpassiveUHFRFIDtagsthatwereattachedtothebuttendofcutlogs.The6-footreadrangeoftheUHFtagallowedlogstobetrackedbyareaderattachedtotheharvesterandtworeaderslocatedatthemill(inalogsortingareaandalogsawingarea)todocumentsupply-chainperformance.

ForestersfromAsia(MalaysiaandSouthKorea)haveperformedpilotstudiesusingRFIDtagsattachedtotreestotestthefeasibilityofusingthetechnologyformonitoringtrees.Mohamedetal.(2009)

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conductedaproof-of-concept-likestudythatreportedonthebenefitsandchallengesofusingRFIDinaforestsetting.Jungetal.(2009)attachedvarioussizedUHFRFIDtagstotreesandcomparedmaximumreaddistanceunderdifferentenvironmentalconditions.Ofthe15differenttagstheytested,themaximumreaddistancewasnomorethan5feet.Largertagstendedtoperformbetterthansmallertagsanddampweathertendedtoaffectreadrange.

III. INVESTIGATION BasedonourreviewofRFIDtechnologyliterature(sectionII),wefeltthatpassiveUHFtagsmightprovideareasonablesolutiontomeetseveralofFIA’sneeds.We,therefore,decidedtoinvestigateseveralmanufacturersofRFIDtechnologythatuseUHFtogainadditionalinformationonthecapabilitiesofpassivetagsandreaders.

Thiswasnotacomprehensive,exhaustiveinvestigation;itwasareasonablesearchofpotentialvendorstogetasenseofwhatthecurrentstate-of-RFID-technology(usingUHF)isrelativetouseforinventoryandmonitoringoftreesintheforestenvironment.WecontactedseveralRFIDmanufacturerstodetermineiftheyhadaproductthatmightmeettheneedsidentifiedinsectionI.A.2,table1.

Don Limuti, electronics engineer, National Technology and Development Center, Missoula, MT conducted the investigation.

A. RFID Tags Investigated 1. Semi-passive tagsDuringthecourseoftheinvestigation,wewereabletoconfirmouroriginalunderstandingofthebenefitsandshortcomingsofsemi-passivetags(sectionII.C).Semi-passivetagshavemuchlongerreadrangesthanpassivetags,butthecurrentcostandshortlifespanofsemi-passivetagsmakethemunacceptableasatoolfortheFIAprogramandmostlikelymakethemimpractical(ornotcosteffective)forotherpotentialuserswithintheNationalForestSystem.Wedidnotinvestigatesemi-passivetagsfurther.

2. Passive tagsSincewesuspectedthatpassivetagsmightprovideareasonablesolutiontomeettheidentifiedneeds,theinvestigationfocusedonthistechnology.Earlyintheinvestigation,itbecameobviousthatonlytagsthatutilizedUHFradiowavestotransmitdatawouldbecapableofprovidingreadrangesclosetothedistancesofinterest(i.e.,>20feet).Assuch,theinvestigationfocusedonlyonpassiveUHFtags.

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WecontactedeightRFIDmanufacturers(seetable2)duringMay–September2013toinquireabouttheirRFIDtags,especiallytheirabilitytomeetouridentifiedneeds(table1)2.BySeptember2013,wehadacquiredsampletagsfortestingfromallmanufacturers.Thepassivetagsprovidedbythemanufacturerscameinmanyshapesandsizes.Sincewewereprimarilyinterestedinthereadrangeofthetags,wewerenotparticularlyconcernedwiththeformfactor(i.e.,packaging,physicalshape,orsize)ofthetag.(SeeappendixAforphotosofseveralofthetagstested.)Inthecourseoftheinvestigation,weperiodicallyaskedthemanufacturersaboutcost.Weneverrequestedaformalquotefromthemanufacturers,butourgeneralsensewasthat$0.45/tag(orgreater)foranorderof100,000+wasprobablymostmanufacturersnegotiatingstartingpoint.

Table 2. RFID manufactures that were contacted for the investigation and the number of tags they provided for testing

RFIDManufacturer Website PointofContact #ofTags

Provided

SAG www.sag.com.twDaniel Yeh danielyeh@sag.

com.tw 4

ZEBRA www.zebra.comStuart_Garney@Identisys.

comwww.identisys.com

3

THINKIFY www.thinkifyit.com

Melissa Beagle, melissa@thinkifyit.com

6

CONFIDEX www.confidex.com

Eric Heinemaneric.heineman@confidex.com 2

FRICK www.fricknet.comBrentHowellBrent.

Howell@fricknet.com 6

VIZINEXRFID

www.vizinexrfid.com

RobertOberleroberle@vizinexrfid.com

2

HIDGlobalCorp.

www.hidglobal.com

David ChoseDchose@hidglobal.com 3

uGROKit www.ugrokit.comLaura Sankey

Laura@UGrokit.com9

Total 35

On5-6November2013,wetestedthetagsattheNationalTechnology&DevelopmentCenter,Missoula, MT (see discussion in section IV).

2 WeconsideredFIAsidentifiedneedforlongreadrangesandlowcost/tagasthemorecrucialneeds.Wefeltifthoseneedscouldnotbesatisfied,FIAwouldnotbeinterestedinwhether(ornot)RFIDtechnologymettheotheridentifiedneeds.

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B. RFID Readers InvestigatedTobeapracticalfieldtool,wefeltthataRFIDreadershouldbelightweight,rugged,andwaterproof.TheRFIDreaderalsoshouldallowforwirelessconnectivitytoalaptopandhaveabout0.5wattsoftransmission(output)powertoprovideforalongreadrange.

Duringthecourseoftheinvestigation,weidentifiedtwoRFIDreadersthatmetmostofthoseparameters:ThinkifyUHFReaderandtheuGROKitReader.ThemanufacturersoftheseRFIDreadersloaned us the devices to use in testing the passive tags.

TheThinkifyRFIDreaderisattachedto(integratedwith)anATid–AT-570mobilecomputer (figure6).Thereaderhas0.8wattsoftransmissionpower.TheuGROKit Reader system uses a smartphone (iOS or Android) attached to a RFID reader (called a Grokker)thatoperateswith0.4wattsoftransmissionpower(figure7).

Figure 6—Thinkify RFID reader (attached to ATiD, AT-570 mobile computer). Top = top view; Bottom = front view

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Figure 7—uGROKit RFID reader (Grokker) attached to mobile phone.

IV. FIELD TESTING THE MAXIMUM READ RANGE OF RFID TAGS AND READERSWetestedthereadrangeoftheRFIDtagsandreadersatMissoula,MT,on5–6November2013.On5NovemberinaconferenceroomattheMissoulaCenterwetestedallRFIDtagsfortheirmaximumreadrange.Sinceweconsideredareadrangeof15feettobeatthelowerendoftheFIAsneed,wefeltthatanytagsthatconsistentlyhad,atleast,thatreadrangewouldbetestedoutdoorstoo. A. Indoor TestWetestedthetagsbyattachingtheRFIDtags(ofagivenmanufacturer)totheconferenceroomwall(usingmaskingtape)andusedtheThinkifyanduGROKitRFIDreaderstodeterminethemaximumreadrange(figure8).Westartedthetestbyreadingthetagswithonereaderatadistanceof2feet.(Note:Thereaderwasrotatedinalldirectionstoobtainatagreading.)From2feetwebackedawayfromthewall(tag)at3-footincrementsuntilwewereattheotherendoftheroom(27feet).ThenwetestedthesametagswiththeotherRFIDreader.Wethenrepeatedtheprocesswithanothermanufacturer’stags.

Figure 8—Indoor testing of maximum read range of uGROKit tags.

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Theresultsofthemaximumreadrangetestareshownintable3.

Table 3—Indoor read ranges of 35 passive RFID tags tested in the study

Thereadrangeofthetagswas2feetto27feet(i.e.,thelengthoftheroom).TheGrokker(i.e.,theuGROKitreader)consistentlyreadfurtherthantheThinkifyreader.

Fromthisindoortest,weselected12tags(shadedingreenintable3)foroutdoortesting.Ingeneral,these12tagsconsistentlyhadareadrangeof15feet(ormore)frombothreaders. B. Outdoor Test Weconductedtheoutdoortestofthe12selectedtagsindividuallyinthefrontparkingareaoftheMissoulaCenter.Weattachedeachtagtoacottonwoodtree(11inchesindiameter).Aswiththeindoortest,westartedthetestbyreadingthetagwithonereaderatadistanceof2feet,facingthedirection

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ofthetag(figure9).(Note:Asintheindoortest,thereaderwasrotatedinalldirectionstoobtainatagreading.)From2feetwebackedawayfromthetree(tag)at3-footincrements(butalwaysdirectlyfacingthetag)untilwecouldnolongerreadthetag.ThesametagwastestedwiththeotherRFIDreader.

Figure 9—Testing read range of RFID tags outdoors. Top - RFID tag taped to cottonwood tree. Bottom - Reading a RFID tag several feet from tree.

Theresultsofthemaximumreadrangetestareshowninfigure10.Noneofthetagsreadfartherthan15feet.Fourofthe12tagshadreadrangesof12to15feet.Themanufacturersofthefourtagswere:Vizinex(#90E785);Zebra(#221605);andThinkify(#204B61and#10E1FC).

Wealsotestedreadingthetagsat45degreesand90degreeswithin6feetofthetree,butreceivedinconsistentreadings.Assuch,wedecidednottosystematicallytestreadingtagsinthismanner.

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Figure 10—Outdoor read ranges of the 12 passive RFID tags tested in the study – using the uGROKit and Thinkify RFID Readers. The four tags above the red line had maximum read ranges of 12 to 15 feet.

V. CONCLUSIONS AND RECOMMENDATIONS AsstatedinsectionI.B,theobjectiveofthisstudywastoinvestigatethecurrentstateofRFIDTechnology–especiallyasitrelatestopractical,cost-effectiveusewithintheforestenvironment. WedeterminedthatthecurrentstateofRFIDtechnologydoesnotmeetthemostcrucialneeds(i.e.,lowcostandlongreadrange)identifiedbytheproposer.NoneoftheRFIDtagsthatwetestedoutdoorshadamaximumreadrangeofmorethan15feet.Also,manufacturersindicatethatthelikelycost/tagwouldbe$0.45/tag(orgreater)for100,000+tags.

IfthecostofpassiveUHFRFIDtagscontinuestodeclineandthereadrangeimproves,thistechnologymaybecomeanincreasinglyattractiveoptionforinventoryingandmonitoringassetsoutdoors.

WediddeterminethatsomemanufacturershaveRFIDtagsthatprovidefairlylongoutdoorreadranges(15feet).Somemanufacturers(Vizinexinparticular)toldusthattheywereworkingactivelyonimprovingthereadrangeoftheirpassiveUHFtags.Also,moreexpensiveRFIDreaders(withmoreoutputpower)mightincreaseoutdoorreadranges.Assuch,amorefocusedcollaborationwithaForestServicesponsor(e.g.,FIA)andaspecificmanufacturer(orafewmanufacturers)mightleadtothedevelopmentofaninexpensivetagwithalongerreadrangeandasuitableformfactor.

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VI. LITERATURE CITEDBjork,A.;Erlandsson,M.;Hakli,J.;Jaakkola,K.;Nilsson,A.;Nummila,K.;Puntanen,V,;Sirkka,A.2010.MonitoringenvironmentalperformanceoftheforestrysupplychainusingRFID.CommutersinIndustry. 62: 830-841.

Ferrer,G.;Dew,N.;Apte,U.2010.WhenisRFIDrightforyourservice.Int.Jour.Prod.Economics.124:414-425.

Ha¨kli,J.;Jaakkola,K.;Pursula,P.;Huusko,M.;Nummila,K.2010.UHFRFIDbasedtrackingoflogsintheforestindustry.In:ProceedingsoftheIEEEconferenceonRFID(IEEERFID2010),April(2010).245–251.

Jung,T.-W.;Koo,J-H.;Kim,K-M,;Pyeon,M-W.2009.ResearchonRFIDsystemrecognitiontestundertheforestryenvironmentfortreemanagement.In:FifthInternationalJointConferenceonINC,IMS,andIDC, Seoul, (2009). 1180–1184.

IntermecTechnologiesCorporation.2007.UHFvs.HFRFID:newinsightsontheolddebate.WhitePaper.Downloadedon8/26/2013at http://www.intermec.com/public-files/white-papers/en/UHFvs.HF_RFID_wp.pdf.

Karygiannis,T.;Eydt,B.;Barber,G.;Bunn,L.;Phillips,T.2007.Guidelinesforsecuringradiofrequencyidentification(RFID)systems.RecommendationsoftheNationalInstituteofStandardsandTechnology.NISTSpecialPublication800-98.

Korten,S.;Kaul,C.2008.ApplicationofRFID(RadioFrequencyIdentification)intheTimberSupplyChain.CroatianJ.ForestEngineering.29:85-94.

Mohamed,N.;Garoot,A.H.;Hazza,Z.M.2009.AcasestudyonimpactofRFIDadoptionintreeinventorymanagement.In:2ndIEEEInternationalConferenceonComputerScienceandInformationTechnology(ICCSIT),Beijing,(2009).624–628.

Roberts,C.M.2006.Radiofrequencyidentification(RFID).Computers&Security.25:18-26.

Ruiz-Garcia,L.;Lunadei,L.2011.TheroleofRFIDinagriculture:applications,limitationsandchallenges.ComputersandElectronicsinAgriculture.79:42-50.

Zhu,X.;Mukhopadhyay,S.K.;Kurata,H.2012.AreviewofRFIDanditsmanagerialapplicationsindifferentindustries.Jour.Eng.&Technol.Manage.29:152-167.

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APPENDIX A. PHOTOS OF RFID TAGS TESTED

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FRICK Tags SAG Tags

THINKIFYTags VIZINEXTags

uGROKit Tags HIDTags